Furnace



FURNACE I 7770/00: (r/ck v A ONEY June 15, 1937. T. CRICK 2,083,641

FURNACE Filed Aug. 26, 1935 2 Sheets-Sheet '2 I 5347 I I {f INVENTOR Thomas (rick BY 'II/IIII/IIIIIIIII Patented June 15, 1937 UNITED STATES FURNACE Thomas Crick, Independence, Mo., assignor to Independence Stove & Furnace Company,

dependence, Mo., a corporation of Missouri Application August 26, 1935, Serial No. 37,914

6 Claims.

This invention relates to heating furnaces and particularly to those wherein gas or gaseous fuels are employed as the heating medium.

In furnaces of this character, the products of combustion are retarded and caused to follow a tortuous path in order to provide maximum absorption of the heat units from the combusted fuel. Consequently, the products of combustion are delivered to the flue at low temperatures and with only suflicient velocity to create the necessary draft to support substantially complete combustion. Therefore, when the fire goes out or the burner fails to light, because of an extinguished pilot light, the passageways soon fill with a highly explosive mixture and serious explosions may result when an attempt is made to relight the burner or pilot light.

The principal objects of the present invention are, therefore, to effect rapid scavenging of the explosive mixture from the radiator passageways and combustion chamber incidental to a step necessary in relighting the burner, to assure complete shut-off of the gas to the burner prior torelighting of the pilot, and to render it physically impossible to apply a light to the pilot until scavenging of the passageways has time to be completed.

In accomplishing these and other objects of the invention as hereinafter pointed out, I have provided improved details of structure, the preferred forms of which are illustrated in the accompanying drawings wherein:

Fig. 1 is a perspective view of a furnace embodying the features of the present invention, parts of which are broken away to better illustrate the construction thereof.

Fig. 2 is a vertical section through the furnace showing the primary and secondary doors in closed position, and the burner valve control lever in the position it assumes when flow of gas is established to the burner.

Fig. 3 is a detail section through the firebox showing the burner valve control lever in the position it assumes when the flow of gas is out off and showing the primary and secondary doors in open position to permit lighting of the pilot light.

Fig. 4 is a detail perspective view of the partition which cooperates with the rear wall of the radiator to form the outlet for the products of combustion.

Fig. 5 is a horizontal section on the line 5-5 Fig. 2.

Fig. 6 is a section through the latch for retaining the master valve control lever in closed position.

Referring more in detail to the drawings:

I designates a furnace particularly constructed for burning gas and which includes a firebox 2, a combustion chamber 3, and a radiator unit 4 enclosed in a jacket 5 wherethrough air to be heated is circulated, as in conventional warm air heating systems.

In the illustrated instance thefire box 2 comprises a box-like structure having an end 6 projecting from the front wall I of the jacket 5 and which is provided with a door opening 8 formed within a frame portion wherethrough the burner ID is installed and serviced. The opening 8 is normally closed by a primary door ll having its bottom edge hingedly connected with the frame 9 by hinge elements l3 so that the door swings downwardly into open position, as shown in Fig. 1.

The door H is provided with draft openings I4 wherethrough combustion supporting air is supplied to the furnace under control of dampers l5 to admit the amount of air necessary in supporting substantially complete combustion.

The firebox communicates through an opening I! with the combustion chamber 3, above mentioned.

The combustion chamber 3 is formed by upward extensions l8 of the sides of the firebox and interconnected plates l9 and 20 extending across the front and rear edges of the opening II. The plate l9 extends vertically and may be formed as a part of the front wall of the radiator, but the plate 20 inclines toward the front to provide an outlet throat 2| opening into the radiator unit. The radiator unit may be of rectangular shape and includes front and rear walls 22-23 and side walls 24-25 connected by top and bottom plates 26 and 21. The rear wall 23 inclines upwardly toward the rear wall 28 of the jacket 5 and the sides and top plate are correspondingly shaped to connect therewith.

Extending transversely of the radiator unit, between the side walls 24 and 25, at a point spaced from the inclined rear wall is a baiiling partition 29 to form a flue chamber 30 gradually increasing in capacity from the bottom toward the top. The partion 29 has foot portions 3i and 32 for spacing the lower edge thereof above the bottom plate 21 to provide indirect outlet openings 33 through which the products of combustion pass into the flue chamber under normal operation of the furnace for indirect discharge through an outlet 34 that is connected with a T joint 35 wherethrough the spent products of combustion are passed to a suitable chimney (not shown).

The radiator unit also includes a plurality of vertical pipes 36 extending vertically therethrough to provide means for baliling the flow of hot gases toward the flue outlet and to increase the radiat- 5 ing surfaces for more efliciently heating the air passing through the jacket 5.

The burner It! may be of any conventional type and has a fuel mixture conduit 31 extending forwardly within the firebox in the direction of the door opening 8 to connect through a primary air supply fitting 33 with a gas supply pipe 39,

connecting with a gas manifold 40, the pipe 39 being equipped with a burner control valve 42 to shut off supply of gas to the burner. The burner is kept lighted while in operation by means of a pilot 43 that is also connected with the gas supply manifold by a pipe 4 5 having a shut-off valve 45 therein.

The construction thus far described operates satisfactorily except in case the pilot light should become extinguished with the gas supply turned on to the burner. When this occurs, an extremely dangerous hazard is created for the reason that a person may attempt to relight the pilot without turning off the gas to the burner or allowing time for the gas filled combustion chamber and radiator to scavenge by reason of the draft created upon opening of the primary door ll.

As above pointed out, the scavenging effect is extremely slow due to the retarded gas travel through the radiator unit, so that even though a substantial time interval has elapsed between shutting off the gas and applying a light to the pilot, an explosive mixture may still be retained in the radiator. Therefore, I provide the furnace with means for automatically increasing the draft through the furnace upon opening the door I I so that the collected gas is quickly scavenged.

This is accomplished by providing the upper end of the partition 29 with a direct gas outlet 4'! located in substantially direct end alignment with the outlet 34 of the flue chamber, whereby a direct draft is created through the furnace to the chimney, which draft is at a much higher velocity than the draft through the outlet openings 33. Consequently, when the burner valve is closed, the gas will quickly scavenge from the combustion chamber. The gas is also drawn from the lower portion of the radiator unit 4 through an induced fiow established by the direct flow through the outlet 4'5.

When the gas is thus scavenged, the pilot may be safely lighted within a few seconds after the gas has been turned off to the burner.

The direct outlet 4'! is formed in an offset 48 of the partition 29, as best shown in Fig. 4. The offset 48 includes an inclined damper seating portion 19 that is connected by triangular shaped sides 59 and El with the body of the partition. A damper 52 is pivoted to ears 53 at the upper edge of the seat and is adapted to remain closed under its own weight as shown in Fig. 2, to normally close off the direct outlet and divert the products of combustion through the radiator and to the flue through the indirect outlets 33.

In carrying out the invention, the damper 52 is connected with the door H by means of a flexible connection such as a chain 54, having one end fixed to a lug 55 on the damper and its other end to the side flange 56 of the door. The chain operates through firebox, combustion chamber and radiator unit and over pulleys 56, 57, and 58, as clearly shown in Fig. 1.

It is thus apparent that whenever the door ll is opened, as shown, it pulls upon the chain to raise the damper and thereby establish a direct outlet for the gases collecting within the furnace. Immediately upon opening of the damper, the gases readily scavenge through the flue, due to the increased draft, but it is desirable to provide other safety features whereby the gas is shut off and the scavenging effect has had time to take place before a fire can be applied to the pilot. This is accomplished by providing the firebox with a partition 59 including a secondary door 6!! that is located between the burner valve 42 and the burner H3. The partition also includes a stationary perforated grill section SI, extending across the lower portion of the firebox and through which the secondary air is supplied to the burner.

The burner and pilot supply conduits 39 and 44 extend through this part of the partition so as not to interfere with the secondary door that preferably is hinged thereto along the upper edge thereof by a rod 62 having its ends mounted in the side walls of the firebox.

The secondary door 60 is preferably of sufficient size to close off the space above the fixed section 6! and has slight openings 63 therein closed by transparent panels 54 to prevent application of a fire to the pilot or burner when the door is closed.

When the burner valve is open, the door is retained closed by means of a lever arm 65 that is attached to the operating member 65 thereof, and has one end bearing against the door 80 to hold it closed, as shown in Figs. 1 and 2. It is therefore, impossible to open the secondary door without moving the lever arm 65 out of position, as shown in Fig. 3, which of course, simultaneously closes the valve and shuts off the gas supply to the burner.

In order to retain the lever 65 in valve closing position, the manifold carries a latch 61 that is pivotally mounted, as at B8, on a bracket 69 and has a pawl portion l0 adapted to engage over the lever 65, as shown in Fig. 5. The latch also includes an actuating arm H which is engaged by a spring 12 to normally retain the lever in latching position.

In using an apparatus constructed and assembled in connection with a furnace as described, and assuming that the burner and pilot light have become extinguished, the furnace will be filled with a highly explosive mixture which would ordinarily result in an explosion if an attempt were made to relight the pilot by an inexperienced person. However, when the door II is opened preparatoryto relighting the pilot, the damper 52 is also opened through the chain connection 54. This establishes a direct outlet for the gas and increases velocity of the draft so that gas is rapidly passed from the furnace. The next step is to close the burner valve 42 by moving the lever arm 85 thereof away from the secondary door and bringing it into engagement with the latch 67. The secondary door 60 is then free to be opened, as shown in Fig. 3. During the interval required to latch the lever arm 65 and open the secondary door, the gases have time to be completely scavenged so that a fire may be safely applied to the pilot 43. The pilot is then lighted.

After lighting the pilot, the secondary door 60 must be closed and the lever arm 65 of the burner valve 42 disengaged from retention with the latch 61. After closing the secondary door, the lever arm 65 is released by pressing upon the arm H to retract the pawl portion 10 thereof. The lever is then swung upwardly against the secondary door to hold it in closed position and to cause opening of the burner valve.

Immediately upon opening the burner Valve, the gas flow is re-established to the burner, which is lighted by the pilot 43. The primary door I i is then closed to also effect closing of the damper 52. After the damper 52 is closed, the products of combustion are diverted through the radiator 4 for flow out through the openings 33.

From the foregoing it is obvious that I have provided a safety feature wherein the pilot light of a gas burner can be safely relighted whenever it has been extinguished. While I have specifically illustrated and described my invention as applied to a gas furnace for warm air heating systems, it is obvious that it may be applied to any similar gas biuning equipment without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A furnace including a combustion chamber having an outlet for products of combustion, a burner in the furnace, a radiator unit connected with the combustion chamber outlet and having indirect and direct flue outlets, a damper in the direct outlet for selectively diverting products of combustion through the radiator unit to the indirect outlet, a duct in the furnace throughwhich access is had to the burner, a guard including perforate air passage means closing the duct to obstruct access to the burner, a door for the duct to control passage of air through said air passage means, and means operably connecting the damper with said control door whereby the damper is opened to create a direct draft through said perforate air passage means, the combustion chamber, radiator unit and through said direct draft outlet when said control door is open to scavenge the combustion chamber and radiator unit.

2. A furnace including a combustion chamber having an outlet for products of combustion, a burner in the furnace, a radiator unit connected with the combustion chamber outlet and having indirect and direct flue outlets, a damper in the direct outlet for selectively diverting products of combustion through the radiator unit to the indirect outlet, a duct in the furnace through which access is had to the burner, a guard including perforate air passage means closing the duct to obstruct access to the burner, a door for the duct to control passage of air through said air passage means, a second door forming a part of said guard to permit access to the burner through said guard, and means operably connecting the damper with said control door whereby the damper is opened to create a direct draft through said perforate air passage means, the combustion chamber, the radiator unit and said direct draft outlet when said control door is opened to scavenge the combustion chamber and radiator unit while said secondary door is being opened.

3. A furnace including a combustion chamber having an outlet for products of combustion, a burner in the furnace, a radiator unit connected with the combustion chamber outlet and having indirect and direct flue outlets, a damper in the direct outlet for selectively diverting products of combustion through the radiator unit to the indirect outlet, a duct in the furnace through which access is had to the burner, a guard including perforate air passage means closing the duct to obstruct access to the burner, a door for the duct to control passage of air through said air passage means, a secondary door forming a part of said guard to permit access to the burner, a gas supply connection for the burner and extending through said duct, a shut-off valve in the supply connection and located between said doors, an operating lever on the valve engaged with the secondary door when the valve is open toretain said secondary door in closed position, and means operably connecting the damper with said control door whereby the damper is opened to create a direct draft through said perforate air means, the combustion chamber, the radiator unit, and through said direct draft outlet when said control door is open to scavenge the combustion chamber and radiator unit while said lever is being actuated to close the valve and to release the secondary door.

4. A furnace including a combustion chamber, a burner in the combustion chamber, a duct in the furnace through which access is had to the burner, a guard including perforate air passage means for closing the duct to obstruct access to the burner, a door for the duct to control passage of air through said air passage means, and a secondary door forming a part of said guard to permit access to the burner through said guard.

5. A furnace including a combustion chamber, a burner in the combustion chamber, a duct in the furnace through which access is had to the burner, a guard including perforate air passage means for closing the duct to obstruct access to the burner, a door for the duct to control passage of air through said air passage means, a secondary door forming a part of said guard for access to the burner, a gas supply connection for the burner extending through said duct, a shut-off valve in the supply connection and located between said doors, and an operating lever on the valve engaged with the secondary door when the valve is open to retain the secondary door in closed position. I

6. A furnace including a combustion chamber, a burner in the combustion chamber, a duct in the furnace through which access is had to the burner, a guard including perforate air passage means for closing the duct to obstruct access to the burner, a door for the duct to control passage of air through said air passage means, a secondary door forming a part of said guard for access to the burner, a gas supply connection for the burner extending through said duct, a shut- 01f valve in the supply connection and located between said doors, an operating lever on the valve engaged with the secondary door when the valve is open to retain the secondary door in closed position, and means for selectively maintaining said lever in valve closing position.

THOMAS CRICK. 

